Huayue Chen

Age-Related Changes in Trabecular and Cortical Bone Microstructure

The elderly population has substantially increased worldwide. Aging is a complex process, and the effects of aging are myriad and insidious, leading to progressive deterioration of various organs, including the skeleton. Age-related bone loss and resultant osteoporosis in the elderly population increase the risk for fractures and morbidity. Osteoporosis is one of the most common conditions associated with aging, and age is an independent risk factor for osteoporotic fractures. With the development of noninvasive imaging techniques such as computed tomography (CT), micro-CT, and high resolution peripheral quantitative CT (HR-pQCT), imaging of the bone architecture provides important information about age-related changes in bone microstructure and estimates of bone strength. In the past two decades, studies of human specimens using imaging techniques have revealed decreased bone strength in older adults compared with younger adults. The present paper addresses recently studied age-related changes in trabecular and cortical bone microstructure based primarily on HR-pQCT and micro-CT. We specifically focus on the three-dimensional microstructure of the vertebrae, femoral neck, and distal radius, which are common osteoporotic fracture sites.

Anatomic variation of the celiac trunk with special reference to hepatic artery patterns

Based on a large homogeneous sample from a Japanese population, anatomic variations in the celiac trunk (CT) and the hepatic artery were studied. Previously we analyzed the branching mode of the CT in 450 Japanese cadavers. In order to maximize the database on the CT and hepatic artery, we examined the anatomy of these arteries in 524 cadavers, a total of 974 cases. A total of 89.8% of cases showed the classical trifurcation of the CT. The typical normal pattern of the CT and the hepatic artery was confirmed in 66.6% and 72.4% of the cadavers, respectively. Variant left and right hepatic arteries were observed in 11.0% and 4.9%, respectively. A variant anatomy involving both the left and right hepatic arteries was found in 1.5%. A common hepatosplenic trunk and a gastrohepatic trunk were seen in 4.4% and 0.3%, respectively. A common hepatic artery (CHA) arising from the superior mesenteric artery (SMA) or directly from the aorta was present in 3.5% or 0.5%, respectively. A hepatosplenomesenteric trunk and a celiomesenteric trunk were encountered in 0.7%, respectively. This anatomical update of the CT and the hepatic artery can be useful for transplantation and general surgeons, as well as vascular radiologists in this area.

Phosphodiesterase-III inhibitor prevents hemorrhagic transformation induced by focal cerebral ischemia in mice treated with tPA.

The purpose of the present study was to investigate whether cilostazol, a phosphodiesterase-III inhibitor and antiplatelet drug, would prevent tPA-associated hemorrhagic transformation. Mice subjected to 6-h middle cerebral artery occlusion were treated with delayed tPA alone at 6 h, with combined tPA plus cilostazol at 6 h, or with vehicle at 6 h. We used multiple imaging (electron microscopy, spectroscopy), histological and neurobehavioral measures to assess the effects of the treatment at 18 h and 7 days after the reperfusion. To further investigate the mechanism of cilostazol to beneficial effect, we also performed an in vitro study with tPA and a phosphodiesterase-III inhibitor in human brain microvascular endothelial cells, pericytes, and astrocytes. Combination therapy with tPA plus cilostazol prevented development of hemorrhagic transformation, reduced brain edema, prevented endothelial injury via reduction MMP-9 activity, and prevented the blood-brain barrier opening by inhibiting decreased claudin-5 expression. These changes significantly reduced the morbidity and mortality at 18 h and 7 days after the reperfusion. Also, the administration of both drugs prevented injury to brain human endothelial cells and human brain pericytes. The present study indicates that a phosphodiesterase-III inhibitor prevents the hemorrhagic transformation induced by focal cerebral ischemia in mice treated with tPA.

Morphology of the Dorsal Lingual Papillae in the Black Rhinoceros (Diceros bicornis)

The dorsal lingual surface of a black rhinoceros (Diceros bicornis) was examined by scanning electron microscopy. The tongue was about 30 cm in length. There were about 60 vallate papillae on both sides. Filiform, fungiform and vallate papillae were found. The filiform papillae were distributed over the entire dorsal surface of the tongue. The papillae had a hair‐like shape. The fungiform papillae were round in shape, and more densely distributed on the ligual apex. No foliate papillae were seen on the dorsal surface. The vallate papillae were located on both sides of the posterior end of the lingual body. Each papilla was surrounded by a groove.

SEM study on the dorsal lingual surface of the flying squirrel, Petaurista leucogenys

The dorsal lingual surface of the flying squirrel was examined by scanning electron microscopy (SEM). Filiform (FI), fungiform (FU), foliate (FO) and vallate papillae (VA) were observed. The FI were distributed over the entire dorsal surface of the tongue. In the region of the VA, the FI appeared as giant cones. The FU were present as rounded bodies scattered over the dorsal surface of the tongue. They were relatively scarce and appear to be concentrated around the edges of the tongue. The FO were observed on the posterolateral regions of the tongue. The flying squirrel showed the triangular arrangement of the three VA, with the apex of the triangle directed posteriorly.

Scanning Electron Microscopic Study of the Tongue in the Owl (Strix uralensis)

The dorsal lingual surfaces of adult owl (Strix uralensis) were examined by scanning electron microscopy. The length of the tongue was about 2 cm. The tip of the tongue of the owl was bifid. Three parts were distinguished in the tongue of the owl: the apex, the body and the root of the tongue. The conical region between the lingual apex and lingual root was a very wide area. There were thread‐shaped processes/cells of epithelium in the lingual apex. The small or large conical papillae were observed on the lingual body. The many openings of the lingual glands existed in the lingual body and lingual root.

Site-specific bone loss in senescence-accelerated mouse (SAMP6): a murine model for senile osteoporosis.

The senescence-accelerated mouse strain P6 (SAMP6) is a model of senile osteoporosis, which possesses many features of senile osteoporosis in humans. So far, little is known about the systemic bone microstructural changes that occur at multiple skeletal sites. In this study, we therefore, investigated site (vertebra, femur and tibia) dependence of bone microstructure and bone mineral density (BMD) in SAMP6 and the normal control mouse (SAMR1) at 5 and 12months of age using quantitative micro computed tomography (micro-CT) and image analysis software. As compared with SAMR1, the most prominent change in SAMP6 was the reduction of vertebral trabecular bone volume fraction (BV/TV) and trabecular BMD. Moderate decrease of trabecular bone mass was observed in the proximal tibia and distal femur. Increased marrow area and periosteal perimeter were investigated, though the cortical area and cortical thickness had no marked changes in the mid-tibial and mid-femoral cortical bones. These results indicate that bone microstructural properties in SAMP6 are remarkably heterogeneous throughout the skeleton, which is analogous to changes that occur in human bones. These findings further validate the relevance of SAMP6 as a model of senile osteoporosis.

Chewing Maintains Hippocampus-Dependent Cognitive Function

Mastication (chewing) is important not only for food intake, but also for preserving and promoting the general health. Recent studies have showed that mastication helps to maintain cognitive functions in the hippocampus, a central nervous system region vital for spatial memory and learning. The purpose of this paper is to review the recent progress of the association between mastication and the hippocampus-dependent cognitive function. There are multiple neural circuits connecting the masticatory organs and the hippocampus. Both animal and human studies indicated that cognitive functioning is influenced by mastication. Masticatory dysfunction is associated with the hippocampal morphological impairments and the hippocampus-dependent spatial memory deficits, especially in elderly. Mastication is an effective behavior for maintaining the hippocampus-dependent cognitive performance, which deteriorates with aging. Therefore, chewing may represent a useful approach in preserving and promoting the hippocampus-dependent cognitive function in older people. We also discussed several possible mechanisms involved in the interaction between mastication and the hippocampal neurogenesis and the future directions for this unique fascinating research.

The osteocyte plays multiple roles in bone remodeling and mineral homeostasis

Osteocytes are the most abundant cells in bone and are the major orchestrators of bone remodeling and mineral homeostasis. They possess a specialized cellular morphology and a unique molecular feature. Osteocytes are a stellate shape with numerous long, slender dendritic processes. The osteocyte cell body resides in the bone matrix of the lacuna and the dendritic processes extend within the canaliculi to adjacent osteocytes and other cells on the bone surface. Osteocytes form extensive intercellular network to sense and respond to environmental mechanical stimulus by the lacunar–canalicular system and gap junction. Osteocytes are long-lived bone cells. They can undergo apoptosis, which may have specific regulatory effects on osteoclastic bone resorption. Osteocytes can secrete several molecules, including sclerostin, receptor activator of nuclear factor κB ligand and fibroblast growth factor 23 to regulate osteoblastic bone formation, osteoclastic bone resorption and mineral homeostasis. A deeper understanding of the complex mechanisms that mediate the control of osteoblast and osteoclast function by osteocytes may identify new osteocyte-derived molecules as potential pharmacological targets for treating osteoporosis and other skeletal diseases.

Bone three-dimensional microstructural features of the common osteoporotic fracture sites

Osteoporosis is a common metabolic skeletal disorder characterized by decreased bone mass and deteriorated bone structure, leading to increased susceptibility to fractures. With aging population, osteoporotic fractures are of global health and socioeconomic importance. The three-dimensional microstructural information of the common osteoporosis-related fracture sites, including vertebra, femoral neck and distal radius, is a key for fully understanding osteoporosis pathogenesis and predicting the fracture risk. Low vertebral bone mineral density (BMD) is correlated with increased fracture of the spine. Vertebral BMD decreases from cervical to lumbar spine, with the lowest BMD at the third lumbar vertebra. Trabecular bone mass of the vertebrae is much lower than that of the peripheral bone. Cancellous bone of the vertebral body has a complex heterogeneous three-dimensional microstructure, with lower bone volume in the central and anterior superior regions. Trabecular bone quality is a key element to maintain the vertebral strength. The increased fragility of osteoporotic femoral neck is attributed to low cancellous bone volume and high compact porosity. Compared with age-matched controls, increased cortical porosity is observed at the femoral neck in osteoporotic fracture patients. Distal radius demonstrates spatial inhomogeneous characteristic in cortical microstructure. The medial region of the distal radius displays the highest cortical porosity compared with the lateral, anterior and posterior regions. Bone strength of the distal radius is mainly determined by cortical porosity, which deteriorates with advancing age.